a. Field of the Invention
This invention relates to acrylic fibers having improved basic dyeability.
b. Description of the Prior Art
It is known to use additives such as vinyl benzene sulfonate as copolymers in making acrylic fibers, the vinyl benzene sulfonate being used to enhance the basic dyeability of the acrylic fibers by providing dye sites. One of the disadvantages of this approach is that these additive monomers are usually expensive. Further, it is very difficult to recover the unreacted portions of monomers of this type. In the past these unreacted monomers have been sewered but this has a double disadvantage in that an expensive monomer is lost and that monomer is non-biodegradable. It would be very desirable to use less of this sulfonated monomer and yet achieve the same or improved basic dyeability.
It is known to use small amounts of styrene as a monomer in making acrylic fibers, the styrene being added to serve as a plasticizer. The styrene is incorporated as a monomer and is copolymerized with the acrylic monomer so as to be an integral part of the polymeric chain. Use of styrene in this manner does not appear to give any improvement in basic dyeability.